Flotation cells are commonly employed to separate solid material from a slurry typically composed of liquids and solids in varying proportions. An impeller located in the flotation cell agitates the slurry dispersing entrapped gas, thereby causing the formation of gas bubbles. Particulate solid material adheres to the surface of the gas bubbles and rises there with to the slurry surface forming a froth that has a higher concentration of the floatable material, as compared to the starting slurry.
The froth, which is a combination of liquid, solid particles, and gas is removed from the flotation cell for further processing. In order to optimize the operation of the flotation cell, it is important to remove the froth at an appropriate rate. Where several flotation cells are operating at one time it is desirable to synchronize their operation, thereby simplifying the control of the individual cells.
A problem often encountered in flotation cell control is due to the non-homogeneous composition of the froth. It is difficult to accurately ascertain the rate at which the froth is being removed from the flotation cell. In the past, ultrasonic level sensors, and magnetic flow meters have been employed, however, the presence of the gaseous phase and the inability of these sensors to detect it has made the readings obtained from these instruments unreliable. Video cameras have also been utilized with little success in an effort to track the speed at which the froth moves toward a peripheral edge of the flotation cell.
Based on the foregoing, it is the general object of the present invention to provide a device for monitoring the rate of froth removal from a flotation cell, that overcomes the problems and drawbacks associated with prior art measurement instruments.
It is a more specific object of the present invention to provide such a device that is capable of measuring froth rate removal and is not affected by the presence of the gaseous phase.